On 6/6/24 10:21 AM, Niklas Cassel wrote: >> Right now, this all works the same way for DM and nvme zns, so I think this >> is >> all good. If anything, we should probably add a warning in the nvme driver >> about the potentially unreliable moz/moz limits if we see a ZNS device with >> multiple zoned namespaces. > > Well, it is only a problem for ZNS devices with NS management. > > If there are two ZNS namespaces on the device, and the device does not > support NS management, the device vendor would have been seriously silly > to not allocate and set the limits in the I/O Command Set Specific Identify > Namespace Data Structure for the Zoned Namespace Command Set correctly. > > But yes, this concern cannot be solved in disk_update_zone_resources(), > which operates on per gendisk (and there is one gendisk per namespace), > so not much this function can do. If we were to do something, it would > have to be done in the nvme driver. > > > Perhaps if the device is ZNS, and does support NS management, but does > not have the Zoned Namespace Resource Management supported bit is set, > divide the MAR/MOR values reported by each namespace by the number of > ZNS namespaces?
Maybe. But that would still not provide any guarantee: a buggy application not respecting the limits would be able to steal resources from the other namespace. In any case, I think this is a discussion to have on the nvme list. -- Damien Le Moal Western Digital Research
